Solar Energy/Transcript
Transcript Text reads: The Mysteries of Life with Tim and Moby Moby and Tim are lying on their backs on towels on a sunny beach. Moby cracks an egg on his chest, and it begins to fry. TIM: Hey, have you been carrying around an egg all day just to do that? Moby produces a spatula and slides it under the frying egg. Tim reads from a typed letter. TIM: Dear Tim and Moby, If fossil fuels pollute the environment, then why don't we just switch over to solar energy? From, Terry. Well, the short answer is that fossil fuels are still much cheaper than solar energy. But unlike fossil fuels, solar power is a renewable source of energy, so researchers are constantly working on ways to harness sunlight. MOBY: Beep. TIM: A renewable energy source is one that comes from a natural, ongoing process that will continue into the foreseeable future. Solar, wind, and hydroelectric power are all renewable energy sources. MOBY: Beep. TIM: Oh, there are lots of ways to harness the sun's energy. Thermal collectors use sunlight to warm water, which is used to heat buildings. An image shows a home with thermal collectors on its roof. TIM: And spacecraft can use solar sails to convert sunlight's force into motion. An illustration shows a satellite far above Earth. It is being pulled along by several large, flat plates arranged in a circle. TIM: But when most people talk about solar energy, they're referring to the use of photovoltaic cells, or solar cells. Those are those dark panels you see on solar powered devices like calculators and satellites. Images show a calculator and a satellite. TIM: Photovoltaic cells convert sunlight directly to electricity. MOBY: Beep. TIM: No, no, sorry. It's too complicated to explain. Moby looks unhappy. TIM: Ah, I'm just kidding. A photovoltaic cell is essentially a thin layer of a semiconductor, like silicon, covered in glass and plastic. A semiconductor is any substance through which an electric current can pass with some effort. An animation shows the sun shining on a photovoltaic cell. TIM: When photons, or light particles, strike the solar cell, they knock an electron loose inside the semiconductor. The space left by that electron gets filled by another electron close by, which leaves its space to be filled, and so on. This chain creates a flow of electrons. An animation illustrates Tim's description. A stream of electrons moves through the photovoltaic cell. MOBY: Beep. TIM: Right. In other words, an electric current. It's a pretty cool technology, but solar cells still have a lot of drawbacks. For one thing, the average cell is only about fifteen to twenty percent efficient. An image shows a large solar panel powering a single light bulb. TIM: That means that they can only convert fifteen to twenty percent of the sunlight that strikes them into electricity. That's enough if you only need to power a calculator, but to power a single home, you'd pretty much have to cover the entire roof in solar panels. An image shows a house with a roof covered in solar panels. TIM: And remember, the Sun isn't always shining. Owners of solar panels have to store up energy for cloudy days, and that's expensive. It begins to rain on the house. Moby stands at a window, frowning. TIM: The price of installing and maintaining these panels ends up costing people up to six times more than just buying electricity from the power company. MOBY: Beep. TIM: Well, because they're still so inefficient, solar panels aren't a good option to power a whole city. It would take a huge area of panels to do that. An image shows rows and rows of solar panels arranged in a desert-like area. TIM: Some cities do utilize solar energy using concentrating solar power plants. These are basically huge mirrors that harness the Sun's energy by reflecting it onto a small area. An image shows the Sun beaming on a tall tower surrounded with mirrors. Arrows indicate sunlight reflecting from the mirrors to the tower. TIM: Of course, any solar power plant is only good for cities in very sunny climates. Hey, speaking of which, let's get in the water. I'm roasting out here. Moby does not reply. Tim looks to his side. Moby is on his back, frying food on his stomach. People are lined up in front of him. A sign reads, Sausage and Onion Sandwiches, $3. TIM: You're not normal. You know that, right? Category:BrainPOP Transcripts Category:BrainPOP Engineering & Technology Transcripts Category:BrainPOP Science Transcripts